555 Configurable Precedence S-R Latch (DPST)

Sset and Sreset should be momentary-contact push-button switches. S3a and S3b should be one double-pole single-throw (DPST) switch. If jumpers are to be used instead, setting of these switches should be a ganged-operation, both open or both close. The designation S3 will be used here to refer to S3a and S3b as a whole. S4a and S4b should be one double-pole single-throw (DPST) switch. If jumpers are to be used instead, setting of these switches should be a ganged-operation, both open or both close. The designation S4 will be used here to refer to S4a and S4b as a whole. Precedence between SET (through TRIGGER/Sset) and RESET (through THRESHOLD/Sreset) can be configured using switches S3 and S4 as tabulated below: S3=OPEN, S4=OPEN Precedence between SET (through TRIGGER/Sset) and RESET (through THRESHOLD/Sreset) is defined by the specific 555 Timer device used (NE555 type or LM555 type). In NE555 set through TRIGGER has precedence over reset through THRESHOLD. In LM555 reset through THRESHOLD has precedence over set through TRIGGER. S3=CLOSE, S4=OPEN RESET (through THRESHOLD/Sreset) has precedence over SET (through TRIGGER/Sset) regardless of the device type. S3=OPEN, S4=CLOSE SET (through TRIGGER/Sset) has precedence over RESET (through THRESHOLD/Sreset) regardless of the device type. S3=CLOSE, S4=CLOSE When Sset and Sreset are simultaneously pressed, no action is performed. No change will be made to the output, Qpp and Qocd simply retain the previous state. Currently only an LM555 model is available in Multisim.